Implement list tenants and routers
Implement list tenants and routers

Add `list_cloud_tenants` and `list_network_routers` function
that returns enterprises and domains,
which are used to test number of cloud tenants and network
routers.

Signed-off-by: sasoc <2f4aaccd011ad03047b9c23ad1fa815fa1870e64@gmail.com>

RedHatQE/mgmtsystem